Pipelines such as those used for the conveyance of oil or water are constructed by welding sections of pipe together. Often, the welding activities will be carried out by automated welding systems at the installation site of the pipeline. In some instances, automated welding systems capable of being moved along the pipeline right-of-way may be used.
Such mobile automated welding systems may comprise a welding carriage and a welding assembly, which includes a torch suitable for Gas Metal Arc Welding (GMAW). The welding carriage is adapted to carry the welding assembly around an annular track or guide mounted externally about one of the pipe sections. Typically, the welding carriage will have a motor for driving the carriage on the guide.
In the field, a variety of welding situations may present themselves. For example, the pipe sections to be welded may have large-angled bevels resulting in broad weld grooves. Conversely, other pipes having deep, thick sections will require that the weld be performed along a narrow weld seam. A flexible welding system is sought that is adaptable to such diverse conditions such that the welding operation can be effected with a single, mobile, apparatus. In addition, the welding system should be flexible enough to enable a substantially constant heat input to the weld.